The Tupolev Tu-128 (NATO reporting name Fiddler) was a long-range interceptor aircraft introduced by the Soviet Union in the 1960s. It had a broad, low/mid-mounted swept wing carrying the main landing gear in wing-mounted pods, and slab tailplanes. Two Lyulka AL-7F-2 turbojet engines were mounted in the fuselage. The two-man crew of pilot and navigator were seated in tandem. The Tu-128, with its maximum weight of 43 tonnes, was the heaviest fighter ever to enter service. It was a pure patrol interceptor, and with its high wing loading, unsophisticated but reliable avionics, and poor visibility, was not an agile aircraft. It was intended to only combat NATO bombers like the B-52, not to dogfight with smaller aircraft. Armament of the Tu-128 was four Bisnovat R-4 air-to-air missiles (known as K-80 during development; NATO reporting name AA-5 'Ash'). Usually two of them were R-4R with semi-active radar homing and two were R-4T infrared-homing missile, with the former on the outer pylons and the latter on the inner underwing pylons. There was no internal weapons bay. Production of the Tu-128 ended in 1970 with total 198 aircraft built. The Tu-128's only publicly reported combat operation was the destruction of NATO reconnaissance balloons. The aircraft remained in service until 1990.